1. Field of the Invention
The instant disclosure relates to a protection circuit of electrostatic discharge (ESD); particularly to a protection circuit of ESD utilized in the Powered Device (PD) of the Power over Ethernet (PoE) system.
2. Description of Related Art
The PoE is generally directed to a system that is capable of transmitting electrical power along with data on Ethernet. And the system generally includes the Power Sourcing Equipment (PSE) and the PD. This technology is especially useful for powering IP telephones, wireless LAN access points, web cameras, hubs, computers and so on, wherein these devices can be supplied with power solely through the twisted pair cable (RJ-45 connector) of the Ethernet, without relying on external power supplies.
Devices adopting the technology of PoE enable electricity and data to transmit through the RJ-45 internet plugs, and as the RJ-45 internet plugs are widely used throughout the modern world, it is contemplated that approximately all the PoE devices are compatible with the current internet environment. Furthermore, the PoE system can supply and cut-off power remotely without the need of changing the Ethernet cable structures, preserving vast amount of resource associated with the power cords.
Furthermore, since the PoE system may suffers damages from the ESD such damages may be minimized when the physical layer receiver of the Ethernet is properly protected. Generally, the protection is implemented within the PoE chip and thus is incapable of providing the system-level ESD protection. Therefore, in order to remain compatible with multiple standards and to ensure the dependability of the system, an extremely fast Schottky diode is used to guide the current into the ground to prevent system from being damaged due to ESD.